Packaging for contact lenses

ABSTRACT

A package ( 10+20+30 ) for contact lenses ( 10 ), especially ‘daily-disposable’ lenses, in which the overall volume of the package and the internal volumes of the lens-holding cavities ( 20 ) in the package are minimised. The packages are preferably multi-cavity packages, with each cavity holding a single lens and all the lenses being inserted into their respective cavities with a common orientation such that a wearer of the contact lenses has the assurance that a lens can always be retrieved from a cavity in a standard orientation. The internal surface ( 24 ) of a cavity preferably deviates from sphericity by being formed with undulations ( 50 ) to break capillary attraction between the lens and the cavity wall ( 24 ) so aiding extraction of the lens from the cavity. On the instructions of an ophthalmic practitioner, packages of suitable lenses can be made up and dispatched by courier or by post to wearer of the lenses.

This is a nationalization of PCT/GB02/05049 filed Nov. 7, 2002 andpublished in English.

The invention relates to a package for contact lenses, in particular of“soft”, daily-disposable contact lenses.

Soft contact lenses have traditionally been packed in glass vialscontaining saline and closed with a ‘rubber’ bung and metal clip. Morerecent the introduction of ‘disposable’ soft contact lenses has resultedin the vial being replaced by a plastic ‘blister’ containing salinefluid and sealed with a vapour-barrier foil. The reason for this changehas been to reduce cost and improve the convenience of opening the pack.Today there are around eight variants of ‘blister’ packs in a variety ofdesigns.

Of the known tyres of blister many rely on a relatively wide opening andoptionally “ramp” features out to one side to facilitate removal of thelens. A significant “headroom” is also provided in the dish, beneath thesealing foil. These dimensions lead inevitably to a certain volume, massand cost of the packaging materials, also being further increased by thevolume of saline fluid included. 1 ml of fluid cavity volume isconsidered adequate for protection of the lens, when filled to 50%,while known packs include almost 2.5 ml cavity volume. For a month'ssupply of lenses, an extra ml of fluid per lens represents an extra 60grams per pack (left eye and right eye). The asymmetrical forms alsorequire moulded extensions to act as “feet” which prevent the packagetipping.

The dimensions of known blisters further bring a risk that the lensbecomes inverted and/or inside-out, in transit, or while being removedby the wearer. Accordingly, the wearer must take special steps to checkthe state of the lens and identify the correct surface before placing onthe eye. This is a major inconvenience. Some known lenses have marksprinted on the lens itself to assist in this process. These marks are ofcourse hard to read, require learning, and add to the cost ofproduction.

The invention aims to provide an improved package for soft contactlenses, particularly of the daily-disposable type.

The invention provides a blister-type package containing at least onecontact lens in a concave cavity, the package having at least two of thefollowing characteristics:

-   A) the cavity is circularly symmetrical;-   B) the radius of curvature in the internal surface of the cavity is    less than 10 mm, preferably in the range 8.5 to 9.0 mm;-   C) the radius of curvature in the internal surface of the cavity is    equal to or within plus or minus 200 micron of the front optical    zone radius, for a −3.00D lens;-   D) the ratio of the internal radius of the packed cavity to the lens    back optical zone radius is less than 1.2, and preferably less than    1.1;-   E) the maximum internal height of the cavity is less than 6 mm;-   F) the vertical clearance between the lens sagittal height and the    internal height of the cavity is less than 2.5 mm, preferably less    than 2.2 mm or even 2.1 mm;-   G) the ratio of cavity sagittal height to lens sagittal height is    less than 1.6;-   H) the diameter of the cavity opening is less than 18 mm and    preferably less than 17 mm; and-   I) the ratio of cavity opening to lens diameter is less than 1.4 and    preferably less than 1.3, 1.25 and 1.2.

A preferred embodiment of the invention has all the above features,although embodiments may be envisaged having fewer than all.

These measures enable an ‘optimum cost’ (low material and shipping cost)blister pack of concave design which also offers distinctive benefits tothe wearer regarding lens removal from the pack. The lens can be removedfrom the opened blister with a single movement and will never be turnedinside-out (provided of course that it is packed consistently thecorrect way). While high-volume manufacturing processes can be designedsuch that the lens is always offered correct-way-out, current blisterdesigns cannot guarantee this lens orientation is maintained duringtransportation and lens removal.

Prior publications U.S. Pat. No. 5,551,964, WO99/27813A (U.S. 6,050,398)and EP 0765815A provide some suggestions to make the radius of thepackage close to that of the lens, and indicate also that the lens willadhere to the package in this case. This can make the lens hard toremove.

Accordingly, the interior of the cavity may be provided with localdeviations from a spherical shape, to allow fluid to enter behind thelens and break capillary attraction between lens and blister.

The package may comprise a plurality of cavities formed integrally in asingle sheet. Alternatively, individual blisters can be attached to asingle sealing foil, to similar effect. Two sheets with sixteen lensesper sheet represents one month's supply for one eye, for example.

The cavities may be sealed with a foil, each cavity containing a lensand preservative fluid. In a preferred embodiment, a single row of(four) blisters would be separated from the sheet. Each blister is thenopened by peeling, one at a time.

The volume of the fluid cavity is preferably in the range 0.9 ml to 1.25ml, and most preferably 0.95 ml to 1.05 ml. This allows for example 0.5ml fluid, and around 0.5 ml headroom to avoid fluid interfering with thesealing process.

The invention in an independent aspect provides a package comprising acontact lens in fluid in a sealed container having an innerlens-supporting surface of generally spherical shape and with curvatureof said surface close to that of the lens, wherein said surface isprovided with formations for preventing the lens adhering to thecontainer surface.

The invention further provides a method of packaging lens or a pluralityof lenses in which a blister package according to the invention as setforth above has each cavity loaded with a contact lens and preservativefluid, and a sealing foil is fixed to the rim of the blister so as tocontain the fluid and lens. The method is preferably performed so as toensure consistent orientation of the lens within each blister.

The invention further provides a method of supplying contact lenses to awearer when a multi-lens package of the type set forth above is producedand dispatched by mail or courier services direct to the wearer. Thisservice is preferably performed on the instruction of an optician.

In each aspect of the invention, the or each contact lens may be a‘daily-disposable’ contact lens intended to be disposed of after beingworn for no more than a single day.

BRIEF DESCRIPTION OF THE DRAWINGS:

Embodiments of the invention will now be described, by way of exampleonly, by reference to the accompanying drawings, in which:

FIG. 1 shows in radial cross-section a contact lens;

FIG. 2 shows in corresponding radial cross-section a blistered portionof a package for the lens of FIG. 1;

FIG. 3 shows in radial cross-section the filled and sealed package;

FIG. 3A shows a complete pack comprising a plurality of blisters andsealed by a common sealing foil.

FIG. 4 illustrates the opening of the package and removal of the lens;

FIG. 5 shows the filled package in a modified embodiment of theinvention; and

FIG. 6 compares the key dimensions of (a) a conventional blister packfor contact lenses and (b) the package of FIGS. 1–5.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a typical contact lens 10, of the type to be packaged. Thelens in this example is of “soft” type, having been moulded at a smallersize and then hydrated to its final size, suitable for wearing. The lenshas front surface 12 and a back surface 14 which contacts the eye inuse.

The lens is approximately part-spherical, ending in a rim 16.

Key dimensions of the lens for the purposes of the present descriptionare marked on the diagram, namely:

-   -   OD_(L), the outside diameter of the lens at the rim 16;    -   BOZR, the back optical zone radius of the lens;    -   R_(L) or FOZR, the front optical zone radius of the lens; and    -   SAG_(L), the front sagittal height of the lens.

It will be appreciated that these dimensions are more or less common toall lenses for normal wear, since the dimensions of the eye are more orless common to different people. OD_(L) is typically between 14.2 and14.3 mm at 20 degrees Celsius, on the assumption that the lenses willshrink to 13.8 mm at body temperature. The lens back optical zone radiusBOZR, ranges in the art from 8.5 mm to 8.7 mm, with one exception 9.0mm, the lens of this embodiment being around 8.6 mm. The front radiusFOZR varies slightly depending on the optical power of the lens (opticalprescription). For the present example a thickness of 0.2–0.3 mm can beassumed, so that the lens front radius on a −3.00D power lens would beapproximately 8.9 mm. −3.00D lenses are the most common andconventionally adopted as typical. On the other hand, the back opticalzone radius is constant for a given product range, and is also publishedvia the Association of Contact Lens Manufacturers (ACLM Contact LensYearbook).

The lens front sagittal height SAG_(L), which is inevitably a functionof OD_(L) and R_(L) ranges from around 3.45 to 3.85 mm in the prior art,and will be 3.82 mm in the present example. These measurements areconventionally done with the lens in an Optimec (Trade Mark) orequivalent instrument, with the lens immersed in a temperaturecontrolled bath of saline fluid at 20 Celsius.

Since the lens is soft it can, either deliberately or inadvertently,become “inside-out” such that the normally concave inner surface 14becomes convex, and the normally convex outer surface 12 becomesconcave. The effect of inserting a soft contact lens into the eye in thewrong orientation is considerable discomfort and inconvenience to thewearer. As explained in the introduction, the novel package describedherein is designed to constrain the lens and prevent inadvertentinversion of its curvature.

FIG. 2 shows in isolation the “blister” or dish portion of a package,adapted to receive lens 10. Blister 20 comprises a part-spherical bowlof plastic material, having outer surface 22, an inner surface 24, and arim 26. Around the rim is a flange 28 including an annular sealingsurface 29. All examples are generally circularly symmetrical. Keydimensions of the blister 20 are as follows:

-   -   OD_(P) is the diameter of the opening, that is the maximum        diameter of the inside surface 24.    -   R_(P) is the radius of curvature of the inside surface 24 of the        blister; and    -   SAG_(P) is the sagittal height of the space inside the blister        in its closed condition (see FIG. 3 below).

FIG. 3 shows a complete pack comprising blister 20 and sealing foil 30,which has been heat-sealed to sealing surface 29 round a flange 28 ofblister 20. Inside the blister is lens 10, bathed in fluid 32. As shownat 20 a and 20 b in broken lines, the package of FIG. 3 typically formsone part of a multi-lens package, for example, containing sixteenindividual blisters in a square array. Two such sheets, nested back toback can form a compact package for one month's supply of lenses for oneeye.

FIG. 3A shows a complete pack comprising a plurality of blisters (20)and sealed by a common sealing foil (30). Alternatively, blisters (20)may be individually sealed by a respective sealing foil.

FIG. 4 shows the package in use. Foil 30 has been peeled back, and thewearer is inserting his or her finger 40 into the package, to engage theinner (concave) surface 14 of the lens. As explained in the introductionand discussed further below, the lens is relatively well confined by thesmall size of the blister. Rather than sliding the lens out of thepackage as in known designs, it has been found that, by pressing thefinger tip gently into the bowl of the lens, the lens can be removedfrom the pack by a single action. The wearer then uses the fingers ofthe other hand to remove the lens from the finger tip and place it onthe eye.

FIG. 5 illustrates a modified package, in which the inner surface 24 ofthe blister has undulations 50. These allow fluid to enter more easilybeneath the lens and so further aid extraction without the need to slidethe lens over the surface. References to the radius of curvature R_(P)of the surface 24 will be understood as referring to the averagecurvature, the undulations representing local deviations from theaverage. The undulations are smooth to avoid lens damage, and supportthe lens typically at four or five places.

FIG. 6 represents schematically a comparison between the dimensions of aconventional blister pack (a) and the pack of FIGS. 1–5 (b). Referencesigns 10 and 20 are used for the lens and package respectively of thepresent design, whilst reference signs with a prime (′) 10′ and 20′refer to the known design. It can be seen that, in the known designs (a)the curvature of the blister 20′ is much gentler than that of the lens10′. The sagittal height is SAG_(P)′ of the blister 20′ is alsosignificantly greater than the height of the lens 10′. In several knowndesigns, there is also a “ramp” or other asymmetrical feature (notshown), providing a slope for removal of the lens by a sliding action.All of these features contribute to the mass and volume of the packageincluding the volume of liquid required. These dimensions alsocontribute to the ability of the lens to become inverted and/orinside-out during handling of the package, leading to inconvenience forthe wearer.

The novel blister 20 (FIG. 6( b)) is designed with a concave cavitywhich follows more closely the contour of the hydrated lens. Thisgenerates a spherical ‘dish’ shape, of radius (curvature) substantiallyequal to the periphery curve of the lens being packaged. For example,for a lens back optical zone radius R_(L) 8.6 mm, the proposed packagehas R_(P) equal to 8.9 mm. The ratio R_(P)/R_(L) is 1.04 in this case.Known packages have R_(P) in the range 10.9 to 12.3 mm.

The inside depth SAG_(P) of the dish is made equal to the front sagittalheight of the lens (front SAG) referred to as SAG_(L) in FIG. 1, plus anamount of “headroom” H=SAG_(P)−SAG_(L) such that the resulting dishvolume is 1 ml (the amount considered the minimum for effective storageof the wet lens, assuming a 50% fill level) whilst also providingsufficient clearance to prevent damage to the lens during the sealing ofthe ‘foil’ (the lid) to the rim of the blister. This gives a depthSAG_(P) for packing a typical soft contact lens of just under 6 mm,compared to values of 6.3 to 8.9 in known packages. The height of thedish may reduce during heat sealing of the foil. The dimensions givenhere refer to the packed state.

It can be calculated that these design ‘rules’ generate an opening(cavity rim diameter) of approximately 17 mm, which is sufficient toallow the wearer to insert the tip of a finger to make contact with theconcave (inside) surface of the lens. Known packages have largeropenings, at least 20 mm, and some also have non-symmetrical extendingportions, supposedly to facilitate removal of the lens. The lens,constrained by the above dish dimensions, will not turn inside out andwill always assume a central position when the pack opening is level.When the wearer, having removed the seal/foil, inserts the soft tip of afinger into the pack liquid the lens will attach itself to the finger bycapillary action making lens removal from the blister very easy and withthe lens predictably positioned. This predictability is of great help tothe wearer since, using other vial or blister packs, the lens will notalways be the correct way-out. Even assuming the lens begins in thecorrect state, in the known packs, it can have been turned inside-out.

The width of annular sealing surface 29 can be as small as 1.5 mm andflange 28 surrounds the dish evenly. This also helps keep theweight/volume of the blister to a minimum, but is sufficiently large foreffective sealing of the foil lid.

The above design results in a filled pack considerably lighter thanthose currently marketed. For example, when compared to other concavedaily-wear-daily-disposable contact lens pack systems the ‘worst-case’(heaviest) comparison pack is over 3 times heavier and the lightestcomparison pack is over 1.5 times heavier.

It will be understood that the invention is not intended to be limitedto the specific examples described above and shown in FIGS. 1–4 and 5.The various dimensions used in these embodiments are examples only, andthe invention extends beyond these examples, and at least within rangesspecified in the introduction and the appended claims.

1. A blister package containing at least one contact lens loaded into arespective concave cavity formed in the package, the package having thecharacteristics (a) the or each cavity is generally circularlysymmetrical; (b) the average radius of curvature in the internal surfaceof the or each cavity is less than 10 millimetres; (c) the verticalclearance between the sagittal height of a contact lens in the packageand the internal height of the respective cavity into which that contactlens is loaded is less than 2.2 millimetres; and (d) the ratio of thediameter of the rim of the or each cavity to the diameter of therespective contact lens loaded into that cavity is less than 1.3;wherein the or each cavity contains a single contact lens and arespective quantity of preservative fluid, and wherein the inner surfaceof the or each cavity is formed as a part-spherical surface withlocalised deviations from part-sphericity, the localized deviationsbeing shaped to allow fluid to enter between that inner surface and thelens so as to break capillary attraction between that inner surface andthe lens.
 2. A package as claimed in claim 1, wherein the radius incharacteristic (b) is in the range 8.5 millimeters to 9.0 millimeters.3. A package as claimed in claim 1, wherein the radius in characteristic(b) is in the range 8.5 to 9.0 millimeters, the vertical clearance incharacteristic (c) is less than 2.1 millimeters, and the ratio incharacteristic (d) is less than 1.2.
 4. A package as claimed in claim 1,the package comprising a plurality of cavities integrally formed in asingle sheet of formable material and individually sealed by arespective sealing foil or by a common single sealing foil.
 5. A packageas claimed in claim 1, the package comprising a plurality ofindividually formed single-cavity blisters each attached to a commonsingle sealing foil.
 6. A package as claimed in claim 4, the saidplurality numbering sixteen.
 7. A package as claimed in claim 1, whereinthe volume of the or each cavity is in the range of volumes from 0.9milliliters to 1.25 milliliters.
 8. A package as claimed in claim 7,wherein the volume of the or each cavity is in the range of volumes from0.95 , milliliters to 1.05 milliliters.
 9. A package as claimed in claim7, wherein the volume of preservative fluid in the or each cavity isbelow 0.6 milliliters.
 10. A package as claimed in claim 7, wherein40%–60% of the internal volume of each cavity is unfilled when eachcavity is loaded with the single respective contact lens together withthe respective quantity of preservative fluid.
 11. A blister packagecontaining at least one contact lens loaded into a respective concavecavity formed in the package, the package having all the characteristicslisted below: (a) the or each cavity is generally circularlysymmetrical; (b) the radius of curvature in the internal surface of theor each cavity is less than 10 millimeters (c) the maximum internalheight of the or each cavity is less than 6 millimeters; (d) thevertical clearance between the sagittal height of a contact lens in thepackage and the internal height of the respective cavity into which thatcontact lens is loaded is less than 2.2 millimeters; and (e) the ratioof the diameter of the rim of the or each cavity to the diameter of therespective contact lens loaded into that cavity is less than 1.3, andwherein the or each cavity contains a single contact lens.
 12. A packageas claimed in claim 11 wherein the radius in characteristic (b) is inthe range 8.5 to 9.0 millimeters, the vertical clearance incharacteristic (d) is less than 2.1 millimeters, and the ratio incharacteristic (e) is less than 1.2.
 13. A method of packaging at leastone contact lens, the method comprising the steps of providing a blisterpackages base defining one of more cavities loading into the or eachcavity in the package base a respective single contact lens togetherwith a respective quantity of preservative fluid, and individuallysealing the or each cavity in a fluid-tight manner either by affixing arespective sealing foil to the respective rim of the or each cavity orby affixing a common single sealing foil to the respective rim of the oreach cavity, the package base being formed so as to result in a packageas claimed in claim
 1. 14. A method as claimed in claim 13 as applied tothe packaging of a plurality of contact lenses, wherein the contactlenses are packaged with mutually consistent orientations.
 15. A methodof supplying contact lenses to a wearer of contact lenses, wherein themethod comprises the steps of packaging at least one contact lens ofappropriate form and dimensions by the method claimed in 13, anddispatching the so-packaged contact lens or contact lenses to the wearerby post or by courier.
 16. A method as claimed in claim 15, wherein thepackaging and dispatch of a contact lens or contact lenses is undertakenon the instructions of an ophthalmic practitioner acting for therespective wearer.
 17. A package as claimed in claim 1, wherein the oreach contact lens is a ‘daily-disposable’ contact lens intended to bedisposed of after being worn for no more than a single day.
 18. A methodas claimed in claim 13, wherein the or each contact lens is a‘daily-disposable’ contact lens intended to be disposed of after beingworn for no more than a single day.
 19. A package as claimed in claim 1wherein said deviations in the cavity surface take the form ofundulations in the surface.
 20. A package as claimed in claim 19 whereinsaid cavity surface with local deviations is smooth.
 21. A method asclaimed in claim 13 wherein said deviations in the cavity surface takethe form of undulations in the surface.
 22. A method as claimed in claim21 wherein said cavity surface with local deviations is smooth.
 23. Apackage as claimed in claim 1, the package further having thecharacteristic (e) the ratio of the internal radius of the packed cavityto the lens back optical zone radius is less than 1.1.